Apparatus and method for measuring two- or three- phase fluid flow utilizing one or more momentum flow meters and a volumetric flow meter

Abstract

An apparatus and method for measuring the flow rates of each component of two-phase flow consisting of a gas and a liquid or three-phase flow consisting of water, oil and gas, including a first volumetric flow-meter stage, and second and third momentum flow meter stages Coupled in a series flow path with the volumetric flow meter stage and in which a velocity ratio between the gas and the liquid in the series flow path is maintained to be one. A processor calculates flow rates of the components of flow by solving volumetric flow and momentum or energy equations defining flow through the first through third stages utilizing a volumetric flow output from the first stage and momentum flux outputs from said second and third stages, and an indicator displays flow of liquid and gas or oil, water and gas components of the flow. To measure three-phase flow, a water-cut meter is provided to determine the amount of water flow, which is then used by the processor to determine the flow of the rest of the liquid. The second and third momentum flow meter stages can be implemented by two separate momentum flow meters or by a single momentum flow meter, such as a venturi flow meter having a venturi nozzle including pressure taps for obtaining at least two differential pressure measurements. In the event that the density of the liquid component is known, a single momentum flow meter stage is sufficient.

What is claimed as new and desired to be secured by Letters Patent of the United States is: 
     
       1. An apparatus for measuring flow rates of gas and liquid components in a fluid flowing in a flow path, comprising: a. volumetric flow meter capable of measuring a total flow rate for a fluid and further capable of outputting a corresponding total flow rate signal;   b. first and second momentum flow meters coupled in series in said flow path with said volumetric flow meter for measuring the momentum flux of a fluid and outputting respective first and second momentum signals; and   c. a processor coupled to said volumetric flow meters and said first and second momentum flow meters, said processor capable of determining the flow rate of a gas component and the flow rate of a liquid component by solving predetermined equations for total flow and momentum or energy utilizing said total flow rate signal and said first and second momentum signals.   
     
     
       2. An apparatus according to claim 1, further comprising at least one of a static mixer or a dynamic mixer capable of forcing a known velocity ratio between said gas component and said liquid component in said flow path. 
     
     
       3. An apparatus of claim 1 further comprising a first and a second mixer coupled in series at an input and an output of said volumetric flow meter. 
     
     
       4. The apparatus of claim 1 further comprising an indicator coupled to said processor, said indicator capable of displaying the determined flow rates of said liquid and gas components. 
     
     
       5. An apparatus of claim 1, wherein said first and second momentum flow meters comprise first and second venturi flow meters having different throat dimensions. 
     
     
       6. An apparatus of claim 1, wherein said first and second momentum flow meter comprise a venturi flow meter having a venturi nozzle including plural pressure measuring taps. 
     
     
       7. An apparatus according to claim 1, wherein said first and second momentum flow meter comprise a drag-disk flow meter having different paddle dimensions. 
     
     
       8. An apparatus according to claim 4, further comprising: a. water-cut meter coupled to said processor and capable of measuring an amount of water in aid liquid component and outputting a corresponding water-cut signal;   b. said processor being capable of determining flow rates of a gas constituent, a water constituent, and a further constituent of said liquid component based on said water-cut signal and the determined liquid and gas flow rates; and   c. said indicator being capable of displaying the determined flow rates of said water constituent and said further constituent.   
     
     
       9. An apparatus according to claim 6, further comprising: a. water-cut meter coupled to said processor and capable of measuring an amount of water in said liquid component and outputting a corresponding water-cut signal;   b. said processor coupled to said processor and being capable of determining flow rates of a gas constituent, a water constituent, and a further constituent of said liquid component in said fluid based on said water-cut signal and the determined liquid and gas flow rates; and   c. said indicator being capable of displaying the determined flow rates of said water constituent and said further constituent.   
     
     
       10. An apparatus according to claim 7, further comprising: a. water-cut meter coupled to said processor and capable of measuring an amount of water in aid liquid component and outputting a corresponding water-cut signal;   b. said processor being capable of determining flow rates of a gas constituent, a water constituent, and a further constituent of said liquid component based on said water-cut signal and the determined liquid and gas flow rates; and   c. said indicator being capable of displaying the determined flow rates of said water constituent and said further constituent.   
     
     
       11. An apparatus according to claim 1, further comprising: a. a pressure differential measuring device capable of measuring a pressure drop across the series flow path of said volumetric flow meter and said first and second momentum flow meters and producing a corresponding pressure drop signal;   b. memory comprising a stored table of differential pressure drops as a function of plural values of air flow rate and water flow rate through said series flow path;   c. device for selecting from said table a corresponding differential pressure drop based on the measured gas and liquid flow rates;   d. a calculating device coupled to receive a pressure drop signal from said pressure differential measuring device and capable of calculating a pressure drop ratio of said pressure drop signal and the selected differential pressure drop and outputting a corresponding pressure drop ratio signal; and   e. a multiplying device coupled to receive a pressure drop ratio signal from said calculating device and capable of multiplying said pressure drop ratio signal with a predetermined signal indicative of a pressure drop of an air/water mixture through a different flow path to determine a pressure drop of said fluid in said different flow path.   
     
     
       12. An apparatus for measuring flow rates of a gas component and a liquid component having a known density in a fluid flowing in a series flow path, comprising: a. volumetric flow meter capable of measuring a total flow rate for a fluid and outputting a total flow rate signal indicative of the measured total flow rate;   b. momentum flow meter coupled in series in said flow path with said volumetric flow meter, said momentum flow meter capable of measuring the momentum flux of said fluid and outputting a corresponding momentum signal;   c. processor coupled to said volumetric flow meter and said momentum flow meter, said processor capable of determining the flow rate of said gas component and the flow rate of said liquid component by solving predetermined equations for total flow and momentum or energy utilizing said total flow rate signal and said momentum signal;   d. a pressure differential measuring device installed in said flow path such that it is capable of measuring the pressure drop across the series flow path of said volumetric flow meter and said momentum flow meter, said measuring device further capable of producing pressure drop signal, indicative of the measured pressure differential;   e. a memory comprising differential drop data stored as a function of plural values of air flow rate and water flow rate through said series flow path;   f. a selection device coupled to said memory, and capable of selecting a corresponding differential pressure drop based on the measured gas and liquid flow rates from said table;   g. a calculating device coupled to receive a pressure drop signal from said pressure differential measuring device and capable of calculating a pressure drop ratio of said pressure drop signal and the selected differential pressure drop and outputting a corresponding pressure drop ratio signal; and   h. a multiplying device coupled to receive a pressure drop ratio signal from said calculating device, said multiplying device capable of multiplying said pressure drop ratio signal with a predetermined signal indicative of a pressure drop of a known mixture through a different flow path to determine a pressure drop of said fluid in said different flow path.   
     
     
       13. An apparatus according to claim 12 further comprising at least one of a static mixer or a dynamic mixer capable of forcing a known velocity ratio between said gas component and said liquid component in said flow path. 
     
     
       14. An apparatus according to claim 12, wherein said volumetric flow meter comprises a positive displacement flow meter. 
     
     
       15. An apparatus according to claim 12, wherein said momentum flow meter comprises a venturi flow meter. 
     
     
       16. An apparatus according to claim 12 further comprising: a. water-cut meter coupled to said processor and capable of measuring an amount of water in aid liquid component and outputting a corresponding water-cut signal;   b. said processor being capable of determining flow rates of a gas constituent, a water constituent, and a further constituent of said liquid component based on said water-cut signal and the determined liquid and gas flow rates; and   c. indicator coupled to said processor and capable of displaying the determined flow rates of said water constituent and said further constituent.   
     
     
       17. A method for measuring flow rates of gas and liquid components in a fluid flowing in a series flow path, comprising: a. measuring a total flow rate in a flow path and outputting a total flow rate signal indicative of the measured total flow rate;   b. measuring the momentum flux of said fluid at first and second points in said series flow path and outputting respective first and second momentum signals; and   c. determining the flow rate of said gas component and the flow rate of said liquid component by solving predetermined equations for total flow and momentum   or energy utilizing said total flow rate signal and said first and second momentum signals.   
     
     
       18. The method of claim 17 further comprising the step of displaying the determined flow rates of said liquid and gas components. 
     
     
       19. A method according to claim 17 further comprising the step of forcing a known velocity ratio between said gas component and said liquid component in said flow path. 
     
     
       20. A method according to claim 17 further comprising the steps of: a. measuring an amount of water in said liquid component and outputting a corresponding water-cut signal;   b. determining flow rates of a gas constituent, a water constituent, and a further constituent of said liquid component in said fluid based on said water-cut signal and the determined liquid and gas flow rates; and   c. displaying the determined flow rates of said water constituent and said further constituent.